The invention relates to the use of phosphine oxide and sulfoxide compounds complexed with transition metals to produce biaryls and arylamines via cross-coupling reactions with aryl halides and arylboronic acids, aryl Grignard reagents, or amines.
Chelating phosphine compounds when bound to metal atoms are generally known to be useful as catalysts. One reaction which uses palladium phosphine catalysts is the coupling of aryl halides with amines for the production of arylamines, as reviewed by Hartwig, SYNLETT, 1997, (4), pg. 329-340. An example of this reaction is the coupling of chlorobenzene and piperidine to form N-phenylpiperidine: 
Another reaction in which palladium/phosphine catalysts have been used is the Suzuki reaction, where biaryls are produced through the coupling of arylboronic acids and aryl halides, as reviewed by Suzuki, A, J. Orgmet. Chem., 576 (1999), pg. 147. One example of this reaction is the preparation of biphenyl from phenylboronic acid and chlorobenzene: 
Both of these products are important classes of compounds widely used in the manufacture of pharmaceuticals, advanced materials, liquid polymers and ligands, and much work has been done on their preparation. However, there is an expanding need for stable, easily prepared catalysts that result in good yields and mild reaction conditions.
Preparation of new ligands has traditionally been performed one at a time after tedious synthesis and purification protocols. Combinatorial techniques have greatly accelerated the discovery of new ligands, but new synthetic schemes are needed. One valuable technique uses solid-phase supports. This solid-phase protocol allows reactions on a polymer-bound scaffold to be driven to completion by using large excesses of reagents in solution that can be easily filtered away from the polymer support. After the scaffold has been modified, an additional cleavage step then frees the small molecule from the polymer support into solution for isolation.
Phosphine oxide compounds and libraries have been prepared using polymer scaffolds in U.S. application Ser. No. 09/415,347 (U.S. Ser. No. 99/23509) which is incorporated in its entirety by reference. Lacking is a process for the convenient preparation of stable arylamines of the formula R1xe2x80x94NR2R3 or biaryls of the formula R1-R6 using a stable phosphine catalyst under mild conditions and producing good yields.
This invention is directed to the use of phosphine oxide compounds complexed with transition metals to produce biaryls and arylamines, arylthiol, arylphosphine oxides and derivatives thereof, via cross-coupling reactions of aryl halides with arylboronic acids, arylmagnesium halides, amines, thiols, and phosphine oxides.
More specifically, the invention is directed twoards a process to prepare biaryls of the formula R1-R7 comprising contacting a Grignard reagent of the formula R7xe2x80x94MgX with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a phosphine oxide compound of the formula HP(O)R4R5, wherein X is a halogen; R1 is an optionally substituted aryl; R7 is selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic; and R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring.
Further, the invention includes a method for the use of phosphine oxides as ligands for homogeneous catalysis biaryls of the formula R1-R7 comprising: (1) preparing a coordination compound comprising one or more transition metals complexed to a phosphine oxide compound of the formula HP(O)R4R5, wherein X is a halogen; R1 is an optionally substituted aryl; R7 is selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic; and R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring; and 2) contacting a Grignard reagent of the formula R7xe2x80x94Mgx with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of the coordination compound prepared in step (1) to form biaryls of the formula R1-R7.
The invention is also directed to a process to prepare biaryls of the formula R1-R7 comprising contacting a Grignard reagent of the formula R7xe2x80x94Mgx with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a phosphine sulfoxide compound of the formula HP(S)R4R5, wherein X is a halogen; R1 is an optionally substituted aryl; R7 is selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic; and R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring.
The invention is further directed to a process to prepare biaryls of the formula R1-R6 comprising contacting a boronic acid of the formula R6xe2x80x94B(OH)2 with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound selected from the group consisting of {[(t-Bu)2P(OH)]2PdCl]}2, [(t-Bu)2P(OH)PdCl2]2, and [(t-Bu)2P(Cl)PdCl2]2, wherein X is a halogen; R1 is an optionally substituted aryl; R6 is selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic; and R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring.
The invention is also directed to a process to prepare biaryls of the formula R1-R6 comprising contacting a boronic acid of the formula R6xe2x80x94B(OH)2 with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a phosphine oxide compound of the formula HP(O)R4R5, wherein X is a halogen; R1 is selected from the group consisting of 3-methoxylphenyl, 2-methoxyphenyl, 4-thiomethoxyphenyl and phenyl; R6 is phenyl; and R4 and R5 are t-butyl.
The invention is also directed to a process to prepare diaryl ketones of the formula R1xe2x80x94C(xe2x95x90O)xe2x80x94R6 comprising contacting a a boronic acid of the formula R6xe2x80x94B(OH)2 with a carbonate salt and an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a phosphine oxide compound of the formula HP(O)R4R5, wherein X is a halogen; R1 is an optionally substituted aryl; R6 is selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic; and R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring.
The invention is also directed towards a process to prepare biaryls of the formula R1xe2x80x94Sxe2x80x94R6 comprising contacting a thiol of the formula R6xe2x80x94SH with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a compound of the formula HP(S)R4R5 or HP(O)R4R5, wherein X is a halogen; R1 is an optionally substituted aryl; R6 is selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic; and R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6, independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring.
The invention is also directed to a process to prepare biaryls of the formula R1xe2x80x94PR10xe2x80x94R6 comprising contacting a compound of the formula KPR6R10 with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a phosphine oxide compound of the formula HP(O)R4R5, wherein X is a halogen; R1 is an optionally substituted aryl; R6 is selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic; R10 is selected from the group consisting of H and R6; and R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring.
A process to prepare arylamines of the formula R1xe2x80x94NR2R3 comprising contacting an amine of the formula HNR2R3 with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound of the formula {[(t-Bu)2P(OH)]2PdCl]}2, [(t-Bu)2P(OH)PdCl2]2, or [(t-Bu)2P(Cl)PdCl2]2, wherein X is a halogen; R1 is an optionally substituted aryl; and R2 and R3 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R2 and R3 can together form a piperidyl ring.
The invention is also directed to a phosphine oxide transition metal complex dimer comprising two transition metal atoms bonded to at least one phosphine oxide ligand each, wherein each transition metal is bonded said ligands via metal-phosphorus bonds, and wherein the two transition metal atoms are bridged via two halogen atoms. Preferably, the phosphine oxide transition metal complex dimer comprises Formula I or Formula II or 
wherein M is a transition metal is selected from Periodic Group VIII; X is a halogen; R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring.
This disclosure sets out methods for the use of phosphine oxide compounds complexed with transition metals to mediate carbon-carbon, carbon-heteroatom bond formations in the generation of biaryls, arylthiols, arylphosphines and arylamines via cross-coupling reactions with aryl halides and arylboronic acids, thiols, phosphine oxides or amines. Phosphine oxides were not previously used as ligands in homogeneous catalysis, primarily because the P-atoms do not have coordinated atoms with lone-pair electrons which were considered essential.
The processes of the instant invention are an improvement over similar processes in the art. The phosphine oxide compounds used in the instant processes are air-stable solids and are easily handled, and can be easily synthesized in a variety of forms using the methods described in U.S. patent application Ser. No. 09/415,347 (U.S. Ser. No. 99/23509). The processes are easily adapted to combinatorial procedures and can be used to construct libraries of biaryls and arylamines, which are themselves widely used in the manufacture of pharmaceuticals, advanced materials, liquid polymers and as ligands. Two examples of compounds or derivatives thereof that could be made by these processes are the synthetic dye Quinizarin Green and p-aminobiphenyl, used as an antioxidant.
Phosphine Oxide Compounds and Libraries
Phosphine oxide compounds of the formula HP(O)R4R5 are known to exist in two tautomeric forms: 
The phosphine oxide compounds can be prepared by any method. One such method is via the use of polymer scaffolds as described in U.S. application Ser. No. 09/415,347 (U.S. Ser. No. 99/23509), herein incorporated by reference. This scheme comprises the steps of contacting (i) a phosphine selected from the group consisting of XPR4R5 and HP(xe2x95x90O)R4R5, wherein X is a halogen, and R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl and heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4 and NQ5Q6, when Q1, Q2, Q3, Q4, Q5 and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbyl amino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring, with (ii) a solid support, resulting in at least one P in the phosphine attached indirectly or directly to the solid support via one or more covalent bonds, and optionally replacing one or more of R4 and R5 with any other R4 and R5 defined above. With this reaction scheme, R4 and R5 can be symmetric, unsymmetric, or chiral.
Virtually any solid material may be used as a support to prepare the phosphine oxide compounds provided it meets the following criteria:
The material is insoluble in organic, aqueous, or inorganic solvents. Organic polymer supports are acceptable in this regard but they generally need to be crosslinked. Inorganic support, such as metal oxides (SiO2, Al2O3, TiO2, ZrO2, etc.), clays, and zeolites, and modified carbons are generally insoluble in these solvents and also may be used as supports.
The support contains reactive sites, which can be used for the covalent attachment of the phosphorus.
The reactive sites are isolated to prevent additional crosslinking during further chemical transformations.
The reactive sites are exposed to the reaction medium. With a polymer resin support this is achieved through the use of a resin which swells in a reaction solvent or is sufficiently porous to allow transport of the reaction medium through the polymer matrix.
The term solid support refers to a material having a rigid or semi-rigid surface that contains or can be derivatized to contain functionality, which covalently links a compound to the surface thereof. Other modifications may be made in order to achieve desired physical properties. Such materials are well known in the art and include, by way of example, polystyrene supports, polyacrylamide supports, polyethyleneglycol supports, metal oxides such as silica, and the like. Such supports will preferably take the form of small beads, pellets, disks, films, or other conventional forms, although other forms may be used.
A preferred solid support is an organic or inorganic polymer to which the phosphorus can be covalently attached through a side chain or pendant group of the polymeric backbone. The polymer may be crosslinked or modified. Suitable preferred polymers useful in the preparation of a supported phosphine compound or a combinatorial library of supported phosphine compounds includes polyolefins, polyacrylates, polymethacrylates, and copolymers thereof that meet the general criteria described above. A more preferred polymeric support is polystyrene wherein the phosphorus is attached to a pendant phenyl group on the polystyrene backbone. Most preferred is polystyrene, crosslinked with divinylbenzene. Specifically, polystyrenes commonly used for solid phase synthesis have been used. These particular resins are crosslinked with from 1 to 10 wt % divinylbenzene. The styrene moieties are substituted in the para or meta positions. Only a portion of the styrene moieties are substituted, typically resulting in functional group loadings of approximately 0.2 to 2.0 mmole per gram of resin, although this value may be higher or lower.
A combinatorial library of phosphine oxides can be used in the instant invention as well as single compounds. To create a library, one or more phosphines are reacted with one or more solid supports, generating a plurality of supported phosphine compounds. Alternatively, a library may be created by reacting one supported phosphine compound with a plurality of cleaving agents, as described below.
As used herein, a combinatorial library is an intentionally created collection of a plurality of differing molecules which can be prepared by selected synthetic means and screened for a desired activity or characteristic in a variety of formats (e.g., libraries of soluble molecules, libraries of compounds attached to resin beads, silica chips, or other solid supports). The libraries are generally prepared such that the compounds are in approximately equimolar quantities, and are prepared by combinatorial synthesis. Combinatorial synthesis refers to the parallel synthesis of diverse compounds by sequential additions of multiple choices of reagents which leads to the generation of large chemical libraries containing related molecules having molecular diversity. Screening methods for libraries vary greatly and are dependent upon a desired activity, the size of library, and the class of compounds in the library.
The libraries can be of any type. These types include but are not limited to arrays and mixtures. Arrays are libraries in which the individual compounds are simultaneously synthesized in spatially segregated locations, typically identified by their location on a grid. Mixture libraries contain a mixture of compounds that are simultaneously synthesized and assayed. Identification of the most active compound is then performed by any of several techniques well known in the combinatorial art, such as deconvolution. (Proc. Natl. Acad. Sci. USA, 91, pg. 10779 (1994)).
A preferred solid support for the combinatorial libraries of the instant invention is an organic or inorganic polymer as described above, to which the phosphorus can be covalently attached through a side chain or pendant group of the polymeric backbone.
One scheme used in attaching the P to the solid support is via the reaction of the halogen or hydrogen bonded to the phosphorus in the phosphine with a nucleophilic group that is covalently attached to a solid support. The term nucleophilic group is well recognized in the art and refers to chemical moieties having a reactive pair of electrons. This scheme can easily be adapted for combinatorial synthesis.
Examples of reactions to prepare the phosphine oxide compounds are shown but not limited to those in Scheme 1 below, where SS is the solid support, X is a halogen, M is any metal, R can be one or more of R4 or R5 as defined above, Z is a divalent attaching group covalently attached to at least one phosphorus in the phosphine, selected from the group consisting of hydrocarbylene, substituted hydrocarbylene, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, and xe2x80x94NRxe2x80x2xe2x80x94, where Rxe2x80x2 is selected from the group consisting of an optionally-substituted hydrocarbyl and halogen, and the Z, O, S, and N substituents are covalently attached to the solid support. 
Any of the substituents in the above compounds may be replaced by other functional groups using any procedure known in the art. One or all of the substituents can be reacted in a single reaction, depending on the choice of reactants and reaction conditions. These reactions can easily be adapted for combinatorial processes. Examples of suitable procedures are shown by but not limited to those depicted in Scheme 2 below, where X, and M are as defined above, and R indicates any of R4 or R5, as defined above. Examples of suitable definitions for M include mg, Li, and Zn. Cp indicates a cyclopentadienyl ring. 
The phosphine oxide compounds are formed by cleaving the compound from the solid support by contacting the supported phosphine with a compound of the Formula ERxe2x80x3, wherein E is an electrophilic group and Rxe2x80x3 is selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heterocycle, organometal, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocycle. Rxe2x80x3 can be optionally replaced by any of R4 or R5. To create a library, one or more supported phosphines are reacted with one or more compounds of the Formula ERxe2x80x3, generating a plurality of phosphine compounds. 
In the above process, E is any electrophilic group that will cleave the covalent bond attaching the phosphorus to the solid support. The term electrophilic group is a term well recognized in the art and refers to chemical moieties, which can accept a pair of electrons from a nucleophilic group as defined above. Suitable electrophilic groups include H, trimethylsilyl, PCl2, halogens, and protons donated from compounds such as acids, alcohols, or amines.
In the instance where ERxe2x80x3 is water, the resulting POH group would rearrange to yield to form the phosphine oxide compounds used in the instant invention. These compounds can also be formed from any other phosphine of the formula RPR4R5 via the replacement of R with an xe2x80x94OH group using any method known in the art. An equivalent rearrangement occurs when a PSH group is present.
Another method for preparing the phosphine oxide compounds is to prepare a phosphine oxide attached to the solid support, as explained above, then to cleave the phosphine oxide directly from the solid support.
After cleavage from the solid support, R4 and R5 may be replaced with any other substituent using any method known in the art, in order to prepare a further range of compounds, such as those described in Encyclopedia of Inorganic Chemistry (John Wiley and Sons, Vol. 6, pg. 3149-3213).
Reactions of Amines with Aryl Halides to Prepared Arylamines of the Formula NHR2R3 
A process is described to prepare arylamines of the formula R1xe2x80x94NR2R3 comprising contacting an amine of the formula HNR2R3 with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a phosphine oxide compound of the formula HP(O)R4R5.
In this process, X is a halogen, R1 is an optionally substituted aryl radical, R2 and R3 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R2 and R3 can together form a ring, and R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4 and NQ5Q6, where Q1, Q2, Q3, Q4, Q5 and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring. Optionally, the process can be performed intramolecularly; i.e. the amine functionality and the aryl functionality are both located on the same compound and the process results in a cyclization.
The amine and the aryl compound can be prepared by any method, including any of the well-known processes in the art.
xe2x80x9cCoordination compoundxe2x80x9d refers to a compound formed by the union of a metal ion (usually a transition metal) with a non-metallic ion or molecule called a ligand or complexing agent.
The transition metals are defined as metals of atomic number 21 through 83. Preferably, the transition metal is from Periodic Group VIII (defined as Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt). More preferred is Pd and Ni. The complex can be made by any synthetic method known in the art, either through direct reaction or via the use of a transition metal precursor.
The phosphine oxide compound is prepared as disclosed above. The phosphine oxide used in the instant invention can exist in either tautomeric form when present as a component of the complex. Examples of this include {[(t-Bu)2P(OH)]PdCl2]}2, {[(t-Bu)2P(OH)]2PdCl]}2, {[(Ph)2P(OH)]2PdCl]}2 where Ph is phenyl, [(Me2CH)2P(OH)]PdCl2]2, [(Cy)2P(OH)]PdCl2]2 where Cy is cyclohexyl. The complex can be isolated and purified before use, or be prepared and used in situ. The phosphine oxide may also be isolated and purified before use, or be prepared and used in situ. Many of these techniques are described in Hartley, F. R. (Ed), Chem. Met.-Carbon Bond, 1987, vol. 4, pp. 1163-1225).
By hydrocarbyl is meant a straight chain, branched or cyclic arrangement of carbon atoms connected by single, double, or triple carbon to carbon bonds and/or by ether linkages, and substituted accordingly with hydrogen atoms. Such hydrocarbyl groups may be aliphatic and/or aromatic. Examples of hydrocarbyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, cyclopropyl, cyclobutyl, cyclopentyl, methylcyclopentyl, cyclohexyl, methyl-cyclohexyl, benzyl, phenyl, o-tolyl, m-tolyl, p-tolyl, xylyl, vinyl, allyl, butenyl, cyclohexenyl, cyclooctenyl, cyclooctadienyl, and butynyl. Examples of substituted hydrocarbyl groups include methoxy, phenoxy, toluyl, chlorobenzyl, fluoroethyl, pxe2x80x94CH3xe2x80x94Sxe2x80x94C6H5, 2-methoxy-propyl, and (CH3)3SiCH2.
By aryl is meant an aromatic carbocyclic group having a single ring (e.g., phenyl), multiple rings (e.g., biphenyl), or multiple condensed rings in which at least one is aromatic, (e.g., 1,2,3,4-tetrahydronaphthyl, naphthyl, anthryl, or phenanthryl), which is optionally mono-, di-, or trisubstituted with, e.g., halogen, lower alkyl, lower alkoxy, lower alkylthio, trifluoromethyl, lower acyloxy, aryl, heteroaryl, and hydroxy. By aryl is also meant heteroaryl groups where heteroaryl is defined as 5-, 6-, or 7-membered aromatic ring systems having at least one hetero atom selected from the group consisting of nitrogen, oxygen and sulfur. Examples of heteroaryl groups are pyridyl, pyrimidinyl, pyrrolyl, pyrazolyl, pyrazinyl, pyridazinyl, oxazolyl, furanyl, quinolinyl, isoquinolinyl, thiazolyl, and thienyl, which can optionally be substituted with, e.g., halogen, lower alkyl, lower alkoxy, lower alkylthio, trifluoromethyl, lower acyloxy, aryl, heteroaryl, and hydroxy.
A preferred process is where R1 is an optionally substituted phenyl, R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl and heterocyclic, and where R2 and R3 are selected from the group consisting of hydrogen, optionally substituted aryl, and where R2 and R3 are hydrocarbyl and together form a ring. More preferred is where X is Cl, Br, or I, R1 is selected from the group consisting of phenyl, 4-methylphenyl, 4-methoxyphenyl and 4-trifluoromethylphenyl, R2 and R3 are selected from the group consisting of hydrogen, phenyl, 4-methylphenyl, and together form a piperidyl ring, and R4 and R5 are selected from the group consisting of t-butyl, phenyl, i-propyl, and 2,4-methoxyphenyl and a piperidyl ring. Also preferably, the transition metal is from Periodic Group VIII. More preferred is Pd, or Ni,
Reactions of Arylboronic Acids, Thiols, Phosphines with Aryl Halides to Prepare Biaryls of the Formula R1-R6, R1xe2x80x94C(xe2x95x90O)xe2x80x94R6, R1xe2x80x94Sxe2x80x94R6, and R1xe2x80x94PR10xe2x80x94R6.
The instant invention also describes a process to prepare biaryls of the formula R1-R6 comprising contacting a boronic acid of the formula R6xe2x80x94B(OH)2 with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a phosphine oxide compound of the formula HP(O)R4R5; where X is a halogen, R1 is an optionally substituted aryl, R6 is selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring. Optionally, the process can be performed intramolecularly; i.e., the boronic acid functionality and the aryl functionality are both located on the same compound and the process results in a cyclization.
A preferred process is where R1 is an optionally substituted phenyl, R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl and heterocyclic, and where R6 is an optionally substituted aryl. More preferred is where X is Cl, Br, or I, R1 is selected from the group consisting of of phenyl, 4-methoxyphenyl, 3-methoxyphenyl, 4-thiomethoxyphenyl, 2-methoxyphenyl and 4-methylphenyl; R6 is selected from the group consisting of 4-methoxyphenyl, and phenyl; and R4 and R5 are selected from the group consisting of t-butyl, phenyl, i-propyl, and 2,4-methoxyphenyl. Also preferably, the transition metal is from Periodic Group VIII. More preferred is Pd and Ni. Also preferred is where the catalyst is {[(t-Bu)2P(OH)]2PdCl]}2, [(t-Bu)2P(OH)PdCl2]2, or [(t-Bu)2P(Cl)PdCl2]2. Most preferred is {[(t-BU)2P(OH)]2PdCl}2.
When a carbonate salt is added to the reaction mixture, diaryl ketones of the formula R1xe2x80x94(Cxe2x95x90O)xe2x80x94R6 are formed. A preferred process is where X is Cl or Br, R1 is phenyl, R6 is phenyl, and R4 and R5 are t-butyl. Also preferably, the catalyst is {[(t-Bu)2P(OH)]2PdCl]}2. The carbonate salt can be any salt that is a source of carbonate (CO3xe2x88x922) ions, preferably a alkali or alkaline earth salt such as K2CO3.
The instant invention also describes a process to prepare biaryls of the formula R1xe2x80x94Sxe2x80x94R6 comprising contacting a thiol of the formula R6xe2x80x94SH with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a phosphine sulfoxide compound of the formula HP(S)R4R5 or a phosphine oxide compound of the formula HP(O)R4R5. R1, R6, R4 and R5 and the phosphine sulfoxides and oxides are as described above. Optionally, the process can be performed intramolecularly; i.e., the thiol functionality and the aryl functionality are both located on the same compound and the process results in a cyclization. A preferred process is where R1 is an optionally substituted phenyl, R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl and heterocyclic, and where R6 is an optionally substituted aryl. More preferred is where X is Cl, Br, or I, R1 is phenyl, R6 is t-butyl or phenyl, and R4 and R5 are t-butyl. Also preferably, the transition metal is from Periodic Group VIII. More preferred is Pd or Ni. More preferred also is where the catalyst is {[(t-Bu)2P(OH)]2PdCl]}2.
Also described is process to prepare biaryls of the formula R1xe2x80x94PR10xe2x80x94R6 comprising contacting a compound of the formula KPR7R10 with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a phosphine oxide compound of the formula HP(O)R4R5. R1, R6, R4 and R5 and the phosphine oxides are as described above, and R10 is selected from the group consisting of H and R6. Optionally, the process can be performed intramolecularly; i.e., the phospine functionality and the aryl functionality are both located on the same compound and the process results in a cyclization. A preferred process is where R1 is an optionally substituted phenyl, R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl and heterocyclic, and where R10 is R6, and R6 are an optionally substituted aryl. More preferred is where X is Cl, and the catalyst is {[R4R5 P(OH)]2PdCl}2, R1 is 4-tolyl or 2-methoxylphenyl, R6 is phenyl, and R4 and R5 are t-butyl. Also preferably, the transition metal is from Periodic Group VIII. More preferred is Pd.
Reactions of Aryl Grignards with Aryl Halides to Prepare Biaryls of the Formula R1-R6 
The instant invention also describes a process to prepare biaryls of the formula R1-R7 comprising contacting a Grignard reagent of the formula R7xe2x80x94MgX with an aryl compound of the formula R1xe2x80x94X in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a phosphine oxide compound of the formula HP(O)R4R5; where X is a halogen, R1 is an optionally substituted aryl, R7 is selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heterocyclic, organometallic, Cl, Br, I, SQ1, OQ2, PQ3Q4, and NQ5Q6, where Q1, Q2, Q3, Q4, Q5, and Q6 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, hydrocarbylamino, alkoxy, aryloxy, and heterocyclic, and optionally R4 and R5 can together form a ring. Optionally, the process can be performed intramolecularly; i.e., the Grignard functionality and the aryl functionality are both located on the same compound and the process results in a cyclization.
A preferred process is where R1 is an optionally substituted phenyl, R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl and heterocyclic, and where R7 is an optionally substituted aryl. More preferred is where X is Cl, R1 is selected from the group consisting of 4-methoxylphenyl and phenyl, R7 is o-tolyl, and R4 and R5 are t-butyl. Also preferably, the transition metal is from Periodic Group VIII. More preferred is Ni.
The process described above to produce biaryls of the formula R1-R7 comprising contacting a Grignard reagent of the formula R7xe2x80x94MgX with an aryl compound of the formula R1xe2x80x94X may also be performed in the presence of a catalytic amount of a coordination compound comprising one or more transition metals complexed to a phosphine sulfoxide of the formula HP(S)R4R5. R1, R7, R4 and R5 are as described above. Optionally, the process can be performed intramolecularly; i.e., the Grignard functionality and the aryl functionality are both located on the same compound and the process results in a cyclization. The phosphine sulfoxides can be prepared using the procedures described above for the phosphine oxides. The phosphine sulfoxide used in the instant invention can also exist in either tautomeric form when present as a component of the complex. The complex can be isolated and purified before use, or be prepared and used in situ. The phosphine sulfoxide may also be isolated and purified before use, or be prepared and used in situ. A preferred process is where R1 is an optionally substituted phenyl, R4 and R5 are independently selected from the group consisting of hydrocarbyl, substituted hydrocarbyl and heterocyclic, and where R7 is an optionally substituted aryl. More preferred is where X is Cl, Br, or I. R1 is selected from the group consisting of 4-methoxylphenyl and phenyl, R7 is o-tolyl, and R4 and R5 are t-butyl. Also preferably, the transition metal is from Periodic Group VIII. More preferred is Ni.
Schemes 1 and 2 to form phosphine oxides and sulfoxides, the cleaving procedures, and the coupling reactions disclosed above are preferably performed under dry, inert atmosphere with dry, deoxygenated solvents. Any solvent is suitable provided that it is inert to all reagents and products. Suitable temperatures for homogeneous catalysis range from xe2x88x9280xc2x0 C. to 200xc2x0 C. Preferred temperatures are about 0xc2x0 C. to about 150xc2x0 C. Preferably a base should be added in the coupling reactions disclosed. Preferred bases are CsF, CsCO3, K2CO3, Na2CO3 and NaOtBu.
The following non-limiting Examples are meant to illustrate the invention but are not intended to limit it in any way.
All manipulations of air-sensitive materials were carried out with rigorous exclusion of oxygen and moisture in flame-dried Schlenk-type glassware on a dual manifold Schlenk line, interfaced to a high-vacuum (10xe2x88x924-10xe2x88x925 Torr) line, or in a nitrogen-filled Vacuum Atmospheres glovebox with a high-capacity recirculator (1-2 ppm of O2). Before use, all solvents were distilled under dry nitrogen over appropriate drying agents (such as sodium benzophenone ketyl and metal hydrides except for chlorinated solvents). Deuterium oxide, THF-D8, C6D6 and chloroform-d were purchased from Cambridge Isotopes (Andover, Mass.). All organic and inorganic starting materials were purchased from Aldrich Chemical Co. (Milwaukee Wis.), Farchan Laboratories Inc. (Gainesville, Fla.), Strem Chemicals (Newburyport, Mass.), Calbiochemxe2x80x94NovaBiochem Corp. (San Diego, Calif.), Rieke Metals, Inc. (Lincoln, Nebr.), or Lancaster Synthesis Inc. (Windham, N.H.), and when appropriate were distilled prior to use.
NMR spectra were recorded on either a Nicolet NMC-300 wide-bore (FT, 300 MHz, 1H; 75 MHz, 13C, 121 MHz 31P), or GE QM-300 narrow-bore (FT, 300 MHz, 1H) instrument. Chemical shifts (xcex4) for 1H, 13C are referenced to internal solvent resonances and reported relative to SiMe4. 31P NMR shifts are reported relative to external phosphoric acid. Analytical gas chromatography was performed on a Varian Model 3700 gas chromatograph with FID detectors and a Hewlett-Packard 3390A digital recorder/integrator using a 0.125 in. i.d. column with 3.8% w/w SE-30 liquid phase on Chromosorb W support. GC/MS studies were conducted on a VG 70-250 SE instrument with 70 eV electron impact ionization.
The polymer bound monophosphines were prepared as described in U.S. patent application Ser. No. 09/415,347 (U.S. Ser. No. 99/23509). The functional groups on the phosphines can be added in two steps to yield unsymmetrical substitutions, or in one step to yield more symmetrical substitution.
A solution of t-butylamine (276 g, 3.78 moles) and KI (0.3 g, 2 mmol) in 1000 mL of THF was treated with chloromethylpolystyrene-divinylbenzene (Merrifield resin, 2% DVB, 75 g, 1.26 mmol/g, 94.5 mmol) while stirring at room temperature for 30 min. The suspension was then refluxed for 24 h before the solution was filtered off. The resulting resin was washed with H2O (3xc3x97250 mL), THF (3xc3x97150 mL), then hexane (3xc3x97200 mL). After drying in vacuum overnight, 75 g of the resin were obtained (98% yield according to N elemental analysis. Anal. calculated for polymer-NHC(Me)3: N, 1.25. Found: N, 1.22). Also the disappearance of 1H resonances of polymer-Phxe2x80x94CH2xe2x80x94Cl (CH2=xcx9c4.5 ppm) and the appearance of 1H resonances of polymer-Phxe2x80x94CH2xe2x80x94NHC(Me)3 (CH2=xcx9c3.7 ppm) indicates that the chloromethyl groups were completely transformed to tert-butylaminometyl groups. Hereafter this will be referred to as Resin I.
A solution of PCl3 (26 g, 189 mmol) in 400 mL of THF was treated slowly with Resin I from above (25 g, 1.21 mmol/g, 30.3 mmol) while stirring at room temperature for a period of 30 min. before Et3N (16 g, 157.5 mmol) was added. The resulting suspension was stirred at room temperature overnight before the solution was filtered off. The resin was washed with hexane (2xc3x9750 mL), CH2Cl2 (5xc3x9780 mL), and hexane (5xc3x9730 mL). The resulting polymer-bound PCl3 resin was dried in vacuum overnight. 31P NMR (122 MHz, CDCl3): xcex4179.1 ppm.
A suspension of the polymer-bound PCl2 resin from above (5.0 g, 1.12 mmol/g, 5.6 mmol) in 150 mL of THF was treated slowly with phenylmagnesium bromide (2 M solution in diethylether, 64 mmol). The resulting mixture was stirred at room temperature for 30 min. before the solution was filtered off and the resin was washed with THF (3xc3x9750 mL), Me2CHOH/THF (20% Me2CHOH, 10 mL), hexane (3xc3x9730 mL). The resulting resin was dried in vacuum overnight to yield polymer-bound PPh2. 31P NMR (122 MHz, CDCl3): xcex452.3 ppm.
A solution of Cl2PPh (33.8 g, 189 mmol) and Et3N (16.0 g, 157.5 mmol) in 500 mL of THF was treated slowly with Resin I (25.0 g, 1.21 mmol/g, 30.3 mmol) while stirring at room temperature for a period of 10 min. The resulting suspension was stirred at room temperature overnight before the solution was filtered off. The resin was washed with THF (50 mL), hexane (3xc3x9750 mL), CH2Cl2 (4xc3x9750 mL), and hexane (2xc3x9750 mL). The resulting polymer-bound PPhCl resin was dried in vacuum overnight. 31P NMR (122 MHz, CDCl3): xcex4135.4 ppm.
A suspension of the resulting resin, the polymer-bound PPhCl, (5.0 g, 1.03 mmol/g, 5.2 mmol) in 150 mL of THF was treated slowly with i-propylmagnesium chloride (0.5 M solution in diethylether, 32.0 mmol). The resulting mixture was stirred at room temperature for 2 h before the solution was filtered off and the resin was washed with THF (3xc3x9710 mL), Me2CHOH/THF (20% Me2CHOH, 5 mL), hexane (3xc3x9730 mL). The resulting resin was dried in vacuum overnight to afford polymer-bound (i-C3H7)PPh. 31P NMR (122 MHz, CDCl3): xcex4655.5 ppm.
The following Experiments illustrate the preparation of the phosphine oxide catalyst used in the method.
A suspension of polymer-bound PPh(CHMe2) prepared as described above (1.25 g, 1.02 mmol/g, 1.28 mmol, 31P NMR (121 MHz, CDCl3): xcex455.5 ppm) and H2O (0.1 g, 4.8 mmol) in THF (10 mL) was refluxed overnight before the resin was filtered off and washed with THF (2xc3x975 mL). The filtrate was dried under vacuum to remove the solvent and excess H2O. The resulting residue was 80 mg (37% yield) of (Me2CH)PH(O)(Ph). It was  greater than 95% pure by 1H NMR and GC/MS. 31P NMR (121 MHz, CDCl3, 1H-decoupled): xcex447.8. 31P NMR (121 MHz, CDCl3, 1H-coupled): xcex447.8 (d, Jp-H=487.7 Hz). 1H NMR (500 MHz, CDCl3): xcex47.74-7.53 (m, 5H), 7.25 (d, Jp-H=487.5 Hz, 1H), 2.33 (m, 1H), 1.12 (m, 6H). 13C NMR (125 MHz, CDCl3): xcex4133.8, 131.1, 129.4, 125.4, 28.0, 14.7. HRMS: Calculated for C9H13PO(M+): 168.0704. Found: 168.0704.
A solution of (Me3C)2PCl (3.0 g, 16.6 mmol, Aldrich) in 5.0 mL of CH2Cl2 was treated with H2O (0.5 g, 27.8 mmol) over a period of 5 min. The resulting reaction mixture was stirred at room temperature for an additional 30 min. Removal of solvent and excess H2O afforded 2.45 g (91% yield) of (Me3C)PH(O)(CMe3). It was  greater than 95% pure by 1H NMR and GC/MS. The pure product was obtained by sublimation (ca. 130xc2x0 C./10xe2x88x923 torr), 31P NMR (121 MHz, CDCl3, 1H-decoupled): xcex469.8 ppm. 31P NMR (121 MHz, CDCl3, 1H-coupled): xcex469.8 (d, Jp-H=434.2 Hz). 1H NMR (500 MHz, CDCl3): xcex45.96 (d, JP-H=434.7 H 1H), 1.14 (d, Hp-H=156.4 Hz, 18H). 13C NMR (125 MHz, CDCl3): xcex433.8 ppm 14 (d, HP-C=58.0 Hz), 25.6 ppm. MS: Calculated for C8H19PO(M+): 162.1. Found: 163.4 (M++H).
A solution of PBr3 (2.5 g, 9.2 mm) in 15 mL of pyridine was treated with 1,3-dimethoxybenzene (2.5 g, 18.1 mm) over a period of 5 min. The resulting mixture was then refluxed for 4 h to give the crude 1-dibromophosphino-2,4-dimethoxybenzene (31P NMR: xcex4159.2 ppm). This compound was used directly for the next step without further purification. Next, polymer-supported secondary amines (10.0 g, 1.1 mmol/g, 11.0 mmol) was slowly added into the mixture above while stirring at room temperature for a period of 10 min. The resulting suspension was stirred at room temperature overnight before the solution was filtered off. The resin was washed with THF (50 mL), hexane (3xc3x9750 mL), CH2Cl2 (4xc3x9750 mL), and hexane (2xc3x9750 mL). The resulting resin was dried in vacuum overnight to yield the polymer-supported P(Br)-2, 4-(MeO)2xe2x80x94C6H3. 31P NMR (122 MHz, CDCl3): xcex4153.8 ppm.
A suspension of this polymer-bound compound (2.0 g, 1.82 mmol, 0.908 mm/g) and I-PrMgBr (12.0 mmol, 1.0 M in THF solution) in 10 mL of THF was refluxed overnight before the solution was filtered off. The resulting resin was washed with THF (3xc3x9720 mL), CH2Cl2 (3xc3x9710 mL), Me2CHOH (2xc3x9710 mL), THF/H2O (70/30 volume ratio, 2xc3x9720 mL) and hexane (3xc3x9710 mL). The resin was dried in vacuum overnight. 31P NMR (122 MHz, CDCl3): xcex460.7 ppm.
A suspension of polymer-bound P(i-Pr)-2, 4-(MeO)2xe2x80x94C6H3 (2.0 g, 1.876 mmol, 0.938 mm/g) and H2O (0.5 g, 28 mm) in 10 mL of THF was refluxed overnight before the resin was filtered off and washed with hexane (3xc3x9710 mL). Removal of solvents and excess H2O from the filtrates by vacuum afforded 100 mg (23% yield) of P(i-Pr)-2, 4-(MeO)2xe2x80x94C6H3. It was  greater than 95% pure by 1H NMR and GC/MS. 31P NMR (202 MHz, CDCl3): xcex435.8 (s) ppm. 31P NMR (1H-coupled, 202 MHz, CDCl3): xcex435.8 (d, HP-H=485.8 Hz) ppm. 1H NMR (500 MHz, CDCl3): xcex47.57 (m, 1H), 7.25 (d, HP-H=485.2 Hz, 1H), 6.48 (m, 1H), 6.37 (m, 1H), 3.76 (d, J=15.2 Hz, 3H), 3.70 (d, J=38.7 Hz, 3H), 2.18 (m, 1H), 1.12-0.81 (m, 6H). 13C NMR (125 MHz, CDCl3): 165.0, 161.8, 135.1, 105.6, 105.5, 98.2, 67.9, 55.6, 27.4, 14.5 ppm. MS: 229.2 (M+1).
A mixture of (Me3C)2PH (5.0 g, 34.2 mm), and S8 (1.096 g, 34.19 mm) in 150.0 mL of 1,4-dioxane was refluxed for 24 h. The resulting mixture was cooled to room temperature and filtered. Removal of solvent followed by sublimation (10xe2x88x923 torr/140) afforded 6.0 g (98% yield) of (Me3C)2PH(S). It was  greater than 95% pure by 1H NMR and GC/MS. 31P NMR (121 MHz, CDCl3, 1H-decoupled): xcex475.8 ppm. 31P NMR (121 MHz, CDCl3, 1H-coupled): xcex476.6 (d, Jp-H=417.1 Hz). 1H NMR (500 MHz, CDCl3): xcex45.84 (d, HP-H=417.3 Hz, 1H), 1.33 (d, Jp-H=16.5 Hz, 18H). 13C NMR (125 MHz, CDCl3): xcex435.8 (d, JP-C=42.2 Hz), 27.3 (d, JP-C=2.46 Hz) ppm. IR (KBr): 2999, 2975, 2952, 2923, 2901, 2864, 2313, 1635, 1470, 1390, 1367, 1360, 1188, 1028, 1014, 903 cmxe2x88x921. HRMS: Calcd for C8H19PS: 179.1023. Found: 179.1018. Anal. Calcd for C8H19PS: C, 53.90; H, 10.74; P, 17.37. Found: C, 53.63; H, 10.60; P, 17.46.
A mixture of Ph2PH (10.0 g, 53.7 mm), and S8 (1.70 g, 53.0 mm) in 150.0 mL of 1,4-dioxane was refluxed for 24 h. The resulting mixture was cooled to room temperature and filtered. Removal of solvent followed by sublimation (10xe2x88x923 torr/150xc2x0 C.) afforded Ph2PH(S). It was  greater than 95% pure by 1H NMR and GC/MS. 31P NMR (121 MHz, CDCl3, 1H-decoupled): xcex423.8 ppm.
Method A
A solution of 32.0 mg (0.112 mm) of Pd(COD)Cl2 and 20.0 mg (0.112 mm) of (t-Bu)2PH(S) in 2.0 mL of THF was boiled under reflux for 12 h. Examination of the reaction mixture by 1H-coupled 31P NMR at this point revealed only a singlet at xcex4145.2 ppm. After filtration, the removal of solvent under vacuum affords a brown solid. 31P NMR (121 MHz, CDCl3, 1H-decoupled): xcex4146.3 ppm. 31P NMR (121 MHz, CDCl3, 1H-coupled): xcex4145.2 (s). 1H NMR (500 MHz, CDCl3): xcex41.40 (d, JP-H=18.4 Hz, 18H) ppm. 13C NMR (125 MHz, CDCl3): xcex445.2 (d, JP-C=40.0 Hz), 27.5 ppm.
Method B
A solution of 50.0 mg (0.0546 mm) of Pd2(dba)3 and 20.0 mg (0.112 mm) of (t-Bu)2PH(S) in 4.0 mL of 1,4-dioxane was boiled under reflux for 12 h. Examination of the reaction mixture by 1H-coupled 31P NMR at this point revealed a singlet at xcex4149.2 ppm as a major component.
Method A
In the dry box, a solution of 1.608 g (8.90 mmol) of (Me3C)2Pxe2x80x94Cl in 50 mL of 1,4-dioxane and 160.0 mg (8.90 mmol) of H2O was stirred at room temperature for 10 min, and 1.0 g (4.45 mmol) of Pd(OAc)2 was gradually added within 5 min. The resulting mixture was then removed from the dry box and refluxed for 5 h. The phosphorus-31 NMR spectrum of the reaction mixture at this point showed the xcex4125.5 (xcx9c5%), 123.5 (xcx9c45%), 123.3 (xcx9c45%) resonances, and no unchanged (Me3C)2PCl and (Me3C)2P(O)H. After cooling to room temperature the mixture was concentrated by rotary evaporation to afford 1.85 g (89% yield) of [Bis-(di-t-butylphosphinous acid)]palladium (I) chloride dimer. 1H NMR (300 MHz, CDCl3): xcex41.37 (d, J=14.57 Hz) ppm. 13C NMR (76 MHz, CDCl3): xcex441.9 (t, J=14.41 Hz), 29.48 (s) ppm. 31P NMR (121 MHz, CDCl3): xcex4124.0 ppm. 1H-coupled 31P NMR (121 MHz, CDCl3): xcex4124.9 (s) ppm. Anal. Calcd for C32H76O4P4Pd2: C, 41.21; H, 8.21; P, 13.28; Cl, 7.60. Found: C, 41.21; H, 8.66; P, 13.28; Cl, 7.54. The crystallographic sample was obtained by slow recrystallization from a mixture of dichloromethane and hexane.
Method B
A 500 mL of round-bottomed flask equipped with magnetic stir bar was charged with 1.469 g (8.90 mm) of (Me3C)2PH(O) which was generated from (Me3C)2PCl and H2O in CH2Cl2, 1.0 g (4.45 mm) of Pd(OAc)2 and 100 mL of 1,4-dioxane. The resulting mixture was then heated to a gentle reflux under open-to-air condition for 20 h. The phosphorus-31 NMR spectrum of the reaction mixture showed the xcex4125.5 (xcx9c5%) and 123.4 (xcx9c95%) resonance, and no unchanged (Me3C)2PH(O). After cooling to room temperature the solution was concentrated by rotary evaporation, the residue was extracted with hexane (10xc3x97100 mL). The extracts were combined, dried under vacuum to afford 1.80 g (87% yield) of yellow solids. It was  greater than 95% pure by 1H and 31P NMR. 31P NMR (121 MHz, CDCl3): xcex4124.0 ppm.
Method C
A 500 mL of round-bottomed flask equipped with magnetic stir bar was charged with 1.160 g (7.15 mmol) of (Me3C)2PH(O), 0.621 g (3.50 mmol) of PdCl2 and 100 mL of THF. The resulting mixture was then heated to a gentle reflux under open-to-air condition for 14 h. The phosphorus-31 NMR spectrum of the reaction mixture showed the xcex4123.5 (xcx9c5%), 122.7 (xcx9c95%) resonances, and no unchanged (Me3C)2PH(O). After cooling to room temperature the solution was concentrated by rotary evaporation to afford 1.80 g (87% yield) of (di-t-butylphosphinous acid)palladium (I) chloride dimer.
Method D
In the dry box, a solution of 4.076 g (22.56 mmol) of (Me3C)2Pxe2x80x94Cl in 135 mL of THF and 407 mg (22.61 mmol) of H2O was stirred at room temperature for 10 min, and 2.0 g (11.28 mmol) of PdCl2 was gradually added within 5 min. The resulting mixture was then removed from the dry box and refluxed for 24 h. The phosphorus-31 NMR spectrum of the reaction mixture at this point showed the xcex4123.5 (xcx9c5%), 122.7 (xcx9c80%) as major resonances. After cooling to room temperature the mixture was concentrated by rotary evaporation to afford 4.30 g (82% yield) of (di-t-butylphosphinous acid)palladium (I) chloride dimer.
Crystal Data
C32H76Cl2O4P4Pd2, from dichloromethane/hexane, light gold, square prism, xcx9c0.20xc3x970.04xc3x970.04 mm, orthorhombic, P212121, a=14.7052(13) xc3x85, b=15.3071(13) xc3x85, c=19.0752(17) xc3x85, alpha=90xc2x0, beta=90xc2x0, gamma=90xc2x0, Vol=4293.7(7) xc3x853, Z=4, T=xe2x88x92100.xc2x0 C. Formula weight=930.49, Density=1.439mg/m3, xcexc(Mo)=1.14 mmxe2x88x921
Data Collection
Bruker SMART 1K CCD system, MoKalpha radiation, standard focus tube, anode power=50 kVxc3x9740 mA, crystal to plate distance=4.9 mm, 512xc3x97512 pixels/frame, multirun data aquisition, total scans=9, total frames=6170, oscillation/frame=xe2x88x920.30xc2x0, exposure/frame=10.0 sec/frame, maximum detector swing angle=xe2x88x9242.0xc2x0, beam center=(254.93,252.33), in plane spot width=1.23, omega half width=0.54, SAINT integration, 1936, hkl min/max=(xe2x88x9219, 17, xe2x88x9220, 20, xe2x88x9225, 25), data collected=40411, unique data=10392, two-theta range=3.42 to 56.60xc2x0, completeness to two-theta 56.60=98.90%, R(int)=0.0677, SADABS correction applied.
Solution and Refinement
Structure solved using XS(Shelxtl), refined using shelxtl software package, refinement by full-matrix least squares on F 2, scattering factors from Int. Tab. Vol C Tables 4.2.6.8 and 6.1.1.4, number of data=10392, number of restraints=0, number of parameters=430, data/parameter ratio=24.17, goodness-of-fit on F2=0.80, R indices[I greater than 4sigma(I)] R1=0.0372, wR2=0.0579, R indices(all data) R1=0.0779, wR2=0.0652, max difference peak and hole=1.398 and xe2x88x920.430 e/xc3x853, refined flack parameter=0.00(12), All hydrogen atoms except H2A and H3A have been idealized as riding hydrogens. The rotation of the methyl groups are refined.
Results
The asymmetric unit contained one molecule with thermal ellipsoids drawn to the 50% probability level. The structure was a racemic twin and the flack parameter had been refined as a full matrix parameter to a value of 0.41(2). The OH group on each side of the molecule formed a symmetric hydrogen bond with the Oxe2x80x94. The +2 charge of each palladium atom was balanced by the O-1 and CL-1 atoms.
Method A
A 500 mL of round-bottomed flask equipped with magnetic stir bar was charged with 1.160 g (7.15 mm) of (Me3C)2PH(O), 1.242 g (7.00 mm) of PdCl2 and 100 mL of THF. The resulting mixture was then heated to a gentle reflux under open-to-air condition for 20 h. The phosphorus-31 NMR spectrum of the reaction mixture showed the xcex4146.96 (singlet, ca. 95%) and 123.0 (singlet, ca. 5%) resonances, and no unchanged (Me3C)2PH(O). After cooling to room temperature, the solution was filtered and concentrated by rotary evaporation to afford 2.0 g of dichloro(di-t-butylphosphinous acid)palladium (II) dimer. 1H NMR (500 MHz, CDCl3): xcex45.23 (m, 1H), 1.43 (d, J=16.3 Hz, 18H) ppm. 13C NMR (125 MHz, CDCl3): xcex442.2 (d, JP-C=25.4 Hz), 28.0 ppm. 31P NMR (CDCl3, 202 MHz): xcex4145.0 ppm. Anal. Calcd for C16H38P2O2C14Pd2: C, 28.3; H, 5.64. Found: C, 27.86; H, 5.47. The crystallographic sample was obtained by slow recrystallization from a mixture of dichloromethane and hexane.
Crystal Data
C8 H19 C12 O P Pd, from dichloromethane/hexane, red/orange, irregular block, xcx9c0.32xc3x970.32xc3x970.16 mm, triclinic, P-1, a=7.8076(10) xc3x85, b=8.0145(10) xc3x85, c=10.4598(10) xc3x85, alpha=84.127(2)xc2x0, beta=84.870(2)xc2x0, gamma=87.923(2)xc2x0, Vol=648.23(13) xc3x853, Z=2, T=xe2x88x92100xc2x0 C., Formula weight=339.50, Density=1.739mg/m3, xcexc(Mo)=1.93 mmxe2x88x921
Data Collection
Bruker SMART 1K CCD system, MoKalpha radiation, standard focus tube, anode power=50 kVxc3x9740 mA, crystal to plate distance=4.9 mm, 512xc3x97512 pixels/frame, hemisphere data aquisition, total scans=4, total frames=1310, oscillation/frame=xe2x88x920.30xc2x0, exposure/frame=8.0 sec/frame, maximum detector swing angle=xe2x88x9228.0xc2x0, beam center=(254.93,252.33), in plane spot width=1.74, omega half width=0.48, SAINT integration, 340, hkl min/max=(xe2x88x9210, 5, xe2x88x9210, 10, xe2x88x9213, 13), data collected=4226, unique data=2937, two-theta range=3.92 to 56.56xc2x0, completeness to two-theta 56.56=91.00%, R(int)=0.0131, SADABS correction applied.
Solution and Refinement
Structure solved using XS(Shelxtl), refined using shelxtl software package, refinement by full-matrix least squares on F 2, scattering factors from Int. Tab. Vol C Tables 4.2.6.8 and 6.1.1.4, number of data=2937, number of restraints=0, number of parameters=129, data/parameter ratio=22.77, goodness-of-fit on F2=1.07, R indices[I greater than 4sigma(I)] R1=0.0243, wR2=0.0666, R indices(all data) R1=0.0265, wR2=0.0682, max difference peak and hole=0.539 and xe2x88x920.941 e/xc3x853, All hydrogen atoms except H1 have been idealized as riding hydrogens. The rotation of the methyl groups are refined.
Results
The asymmetric unit contained one half of the molecule with thermal ellipsoids drawn to the 50% probability level.
Method B
A solution of 2.0 g (7.00 mmol) of Pd(COD)Cl2 and 1.16 g (7.03 mmol) of (t-Bu)2PH(O) in 100 mL of 1,4-dioxane was boiled under reflux for 17 h. Examination of the reaction mixture by 1H-coupled 31P NMR at this point revealed only a singlet at xcex4147.6 ppm. Solvent was removed from filtrate in vacuo and the residue was dissolved in CH2Cl2. Evaporation of the filtrate in vacuum followed by crystallization from a mixture of CH2Cl2/hexane (95:5 volume ratio) gave 2.0 g (84% yield) of dark brown [(t-Bu)2Pxe2x80x94(OH)PdCl2]2. 1H NMR (500 MHz, CDCl3): xcex45.23 (m, 1H), 1.43 (d, J=16.3 Hz, 18H) ppm. 13C NMR (125 MHz, CDCl3): xcex442.2 (d, JP-C=25.4 Hz), 28.0 ppm. 31P NMR (CDCl3, 202 MHz): xcex4145.0 ppm.
Method C
In the dry box, a solution of 1.019 g (5.64 mmol) of (Me3C)2Pxe2x80x94Cl in 100 mL of THF and 102 mg (5.64 mmol) of H2O was stirred at room temperature for 10 min, and 1.0 g (5.64 mmol) of PdCl2 was gradually added within 5 min. The resulting mixture was then removed from the dry box and refluxed for 6 h. The phosphorus-31 NMR spectrum of the reaction mixture at this point showed the xcex4146.6 (singlet, ca. 70%) and 122.7 (singlet, ca. 30%) resonances. After the resulting mixture was refluxed for another 18 h, the crude product was shown by its phosphorus-31 NMR spectrum to be a mixture of the title complex 2 and di-t-butylphosphinechloride palladium chloride dimer with a phosphorus-31 NMR spectrum of xcex4164.7 (singlet) as major components in approximately equal amounts.
A solution of 3.0 g (10.5 mmol) of Pd(COD)Cl2, 1.898 g (10.5 mmol) of (t-Bu)2Pxe2x80x94Cl and 200 mg (11.1 mmol) of H2O in 100 mL of THF was boiled under reflux for 14 h. Examination of the reaction mixture by 1H-coupled 31P NMR at this point revealed only a singlet at xcex4164.7(singlet) ppm. After cooling to room temperature, the reaction mixture was filtered, and the residue was washed with CH2Cl2 (20 mL). Solvents were removed by rotary evaporation, and the resulting residue was washed with hexane (8xc3x9750 mL), dried in vacuo gave 3.2 g of dark brown [(t-Bu)2P(Cl)PdCl2]2. The crystallographic sample was obtained by slow recrystallization from a mixture of dichloromethane and hexane.
Crystal Data
C8 H18 C13 P Pd, from dichloromethane/hexane, red/orange, wedge, xcx9c0.150xc3x970.140xc3x970.050 mm, orthorhombic, Pca21, a=14.8290(13) xc3x85, b 11.9397(10) xc3x85, c=14.7623(13) xc3x85, Vol=2613.7(4) xc3x853, Z=8, T=xe2x88x92120.xc2x0 C., Formula weight=357.94, Density 1.819mg/m3, xcexc(Mo)=2.11 mmxe2x88x921.
Data Collection
Bruker SMART 1K CCD system, MoKalpha radiation, standard focus tube, anode power=50 kVxc3x9740 mA, crystal to plate distance=4.9 mm, 512xc3x97512 pixels/frame, hemisphere data aquisition , total scans=4, total frames=1330, oscillation/frame=xe2x88x920.30xc2x0, exposure/frame=30.0 sec/frame, maximum detector swing angle=xe2x88x9228.0xc2x0, beam center=(254.93,252.33), in plane spot width=1.46, omega half width=0.81, SAINT integration, hkl min/max=(xe2x88x9219, 16, xe2x88x9215, 15, xe2x88x9219, 16), data input to shelx=16611, unique data=5405, two-theta range=3.42 to 56.58xc2x0, completeness to two-theta 56.58=98.20%, R(int-xl)=0.0216, SADABS correction applied.
Solution and Refinement
Structure solved using XS(Shelxtl), refined using shelxtl software package, refinement by full-matrix least squares on F 2, scattering factors from Int. Tab. Vol C Tables 4.2.6.8 and 6.1.1.4, number of data=5405, number of restraints=1, number of parameters=247, data/parameter ratio=21.88, goodness-of-fit on F2=1.06, R indices[I greater than 4sigma(I)] R1=0.0174, wR2=0.0448, R indices(all data) R1=0.0181, wR2=0.0452, max difference peak and hole=0.768 and xe2x88x920.427 e/xc3x853, refined flack parameter=xe2x88x920.005(16), All hydrogen atoms have been idealized as riding hydrogens. The rotation of the methyl groups are refined.
Results
The asymmetric unit contains one molecule with thermal ellipsoids drawn to the 50% probability level.
Method A
In the dry box, a solution of 1.964 g (8.90 mmol) of Ph2Pxe2x80x94Cl in 100 mL of 1,4-dioxane and 180.0 mg (10.0 mmol) of H2O was stirred at room temperature for 10 min, and 1.0 g (4.45 mmol) of Pd(OAc)2 was gradually added within 5 min. The resulting mixture was then removed from the dry box and refluxed for 20 h. The phosphorus-31 NMR spectrum of the reaction mixture at this point showed the xcex478.1 (xcx9c70%), 30.2 [xcx9c30% Ph2P(O)H]resonances.
Method B
In the dry box, a solution of 13.1 g (56.4 mmol) of Ph2Pxe2x80x94Cl in 100 mL of THF and 1.2 g (66.7 mmol) of H2O was stirred at room temperature for 10 min, and 5.0 g (28.2 mmol) of PdCl2 was gradually added within 5 min. The resulting mixture was then removed from the dry box and refluxed for 15 h. The phosphorus-31 NMR spectrum of the reaction mixture at this point showed the xcex478.6 (xcx9c30%), 29.1 [xcx9c70% Ph2P(O)H] resonances.
Method A
In a dry box, a solution of 0.35 g (2.29 mmol) of (Me2CH)2Pxe2x80x94Cl in 10 mL of CH2Cl2 was treated with 100 mg (5.5 mmol) of H2O within 5 min. The resulting mixture was then removed from the dry box and refluxed for 10 min. The phosphorus-31 NMR spectrum of the reaction mixture at this point showed the xcex465.7 resonance. The reaction mixture was dried under vacuum to afford 0.21 g (68% yield) of crude product.
Method B
A solution of 3.43 g (21.56 mmol) of (Me2CH)2Pxe2x80x94Cl in 80 mL of hexane was treated with 835 mg (46.4 mmol) of H2O within 5 min. The resulting mixture was stirred at room temperature for 24 h. The phosphorus-31 NMR spectrum of the reaction mixture at this point showed the xcex465.7 resonance. The reaction mixture was dried under vacuum to afford 2.8 g (97% yield) of crude product.
In a dry box, a solution of 0.42 g (1.80 mmol) of Cy2Pxe2x80x94Cl in 10 mL of CH2Cl2 was treated with 100 mg (5.5 mmol) of H2O within 5 min. The resulting mixture was then removed from the dry box and refluxed for 10 min. The phosphorus-31 NMR spectrum of the reaction mixture at this point showed the xcex459.7 resonance. The reaction mixture was dried under vacuum to afford 0.30 g (78% yield) of crude product.
In a dry box, a solution of 1.0 g (6.29 mmol) of (Me2CH)2Pxe2x80x94Cl in 35 mL of THF and 0.4 g (22.2 mmol) of H2O was stirred at room temperature for 10 min, and 1.115 g (6.29 mmol) of PdCl2 was gradually added within 5 min. The resulting mixture was then removed from the dry box and refluxed for 15 h. The phosphorus-31 NMR spectrum of the reaction mixture at this point showed the xcex4138.2 (xcx9c70%), 117.8 {xcx9c20%, [(Me2CH)2P(OH)]2PdCl]2} and 63.5 [xcx9c10%, (Me2CH)2PH(O)] resonances. After solvents were removed by rotary evaporation, the residue was washed with hexane (10xc3x9715 mL), dried under vacuum to afford 1.4 g (72% yield) of yellowish solids with 31P NMR: xcex4142.5 ppm.
In a dry box, a solution of 1.0 g (4.297 mmol) of Cy2Pxe2x80x94Cl in 10 mL of THF and 0.4 g (22.2 mmol) of H2O was stirred at room temperature for 10 min, and 762 mg (4.297 mmol) of PdCl2 was gradually added within 5 min. The resulting mixture was then removed from the dry box and refluxed for 16 h. The phosphorus-31 NMR spectrum of the reaction mixture at this point showed the xcex4133.1 resonance. After solvents were removed by rotary evaporation, the residue was washed with hexane (8xc3x9720 mL), dried under vacuum to afford 1.45 g (86% yield) of crude [(Cy)2P(OH)]PdCl2]2.
A 50 mL of reactor equipped with magnetic stir bar was charged with 186 mg (0.20 mmol) of {[(t-Bu)2P(OH)]2PdCl}2, 1.57 g (10.0 mmol) of bromobenzene, 1.62 g (10.0 mmol) of di-tert-butylphosphine oxide and 1.38 g (10.0 mmol) of K2CO3 in 20.0 mL of 1,4-dioxane. The resulting mixture was refluxed for 23 h to afford di-tert-butylphenylphosphine oxide. 31P NMR (CDCl3, 121 MHz): xcex451.9 ppm.
A 20 mL of reactor equipped with magnetic stir bar was charged with 93 mg (0.10 mmol) of {[(t-Bu)2P(OH)]2PdCl}2, 0.314 g (2.0 mmol) of bromobenzene, 0.404 g (2.0 mmol) of di-phenylphosphine oxide and 0.276 g (2.0 mmol) of K2CO3 in 5.0 mL of 1,4-dioxane. The resulting mixture was refluxed for 8 h to afford tri-phenylphosphine oxide. 31P NMR (CDCl3, 121 MHz): xcex430.3 ppm.
Synthesis of Cy2Nxe2x80x94PCl2: A mixture of 34.4 g (0.25 moles) of PCl3 in 400 mL of hexane was treated with Cy2NH (90.7 g, 0.50 moles) dropwise at xc2x0 C. for 30 min. The resulting white slurry was warmed to room temperature and stirred for 1 h, refluxed overnight before removal of Cy2NHxe2x80x94HCl by filtration. The white solids were washed with hexane (2xc3x97100 mL). The combined filtrates were concentrated to give the crude Cy2Nxe2x80x94PCl2 (54.0 g, 77% yield). 31P NMR (121 MHz, CD2Cl2): xcex4171.3 (s) ppm.
Synthesis of (R, R) Cy2Nxe2x80x94P(2, 5-Me2C4H6): A solution of 2.0 g (7.09 mm) of Cy2Nxe2x80x94PCl2 in 150 mL of THF was treated dropwise with LiAlH4 (7.1 mL of a 1.0 M solution in Et2O) at room temperature for 10 min and then the resulting reaction mixture was stirred at room temperature for an additional 2 h. The reaction process was monitored by 31P NMR which indicated only a singlet at xcex4xe2x88x9269.2 ppm. The THF solvent was removed under vacuum, and the residue was extracted with 3xc3x9750 mL of hexane. After addition of 100 mL of THF to the extracts, 5.6 mmol (3.5 mL of 1.6 M solution in hexane) of n-BuLi was added to the solution above dropwise. The resulting mixture was stirred at room temperature for 2 h before 1.0 g (5.55 mmol ) of (2S, 5S)-2,5-hexanediol cyclic sulfate in 10 mL of THF was added to the mixture dropwise. After the solution was stirred for 1.5 h, n-BuLi (3.8 mL of a 1.6 M hexane solution, 1.1 eq) was again added dropwise via syringe. The resulting reaction mixture was allowed to stirr overnight at room temperature before 3.0 mL of MeOH was added to quench excess n-BuLi remaining. After removal of solvent, the solid residue was extracted with hexane (4xc3x9760 mL), Concentration of the filtrate affords a crude product. MS: 312.2 [M(O)++H].
Synthesis of (R, R)(2, 5-Me2C4H6)PH(O): A solution of 1.0 g (3.39 mmol) of of (R, R) Cy2Nxe2x80x94P(2, 5xe2x80x94Me2C4H6) and 10 mL of HCl-ether solution (1.0 M in Et2O) was stirred at room temperature for 2 h to afford a crude title compound.
Synthesis of (R, R)(2, 5xe2x80x94(Me2CH)2C4H6)PH(O): A suspension of polymer-bound N(t-Bu)PCl2 (xcx9c20 g, xcx9c17.8 mmol) and LiAlH4 (100 mL, 100 mmol, 1.0 M solution in Et2O) in 200 mL of THF was stirred at room temperature for 2 h before the solvents and excess reagent were filtered off. The resulting resin was washed with THF (3xc3x97100 mL) and hexane (3xc3x97100 mL) before n-BuLi (64 mmol, 1.6 M solution in hexane) was added. The suspension was stirred at room temperature over 3 h before the excess reagent and solvent were filtered off. The resulting resin was washed with THF (3xc3x9750 mL) and hexane (2xc3x97100 mL). The resin above and 3.1 g of (2S, 5S)-2,5-(i-Pr)2C4H6SO4 (cyclic sulfate) in 300 mL of THF were stirred at room temperature overnight before n-BuLi (20.0 mmol, 1.6 M solution in hexane) was added. The mixture was stirred at room temperature for 4 h, and the solvents and excess reagents were filtered off. The resulting resin was washed with THF (2xc3x97150 mL), hexane (2xc3x97150 mL) and CH2Cl2 (2xc3x97100 mL). The resin above and HCl-ether solution were stirred at room temperature to afford a crude title compound.